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Gear / Technical Help => Post-Processing, Computer / Streaming / Internet Devices & Related Activity => Topic started by: taylordb on April 22, 2007, 02:31:22 PM

Title: Need Audacity help in reducing spike
Post by: taylordb on April 22, 2007, 02:31:22 PM
I recently recorded Umphrey's McGee and need some advice on how to handle a situation with Audacity.  Right now the entire show is in one large wav file.  The last thing I will do is break it up into individual tracks.  To bring the levels up so I don't have to crank up my playback system I want to select the entire file and either normalize or amplify (I still need to figure out what the real difference is) to the maximum extent without clipping.  My problem is that I have one very small instant in the recording where there is a spike.   This spike will control the amount of amplification that will be made to the entire show (because the spike is the part that will clip 1st).  Is there any way in Audacity to reduce that one spike to a lower level?  I have looked into the draw function, but I have to be zoomed in so tight that I loose perspective in what I am doing.  Just wondering if anyone has experience in this.

Thanks so much in advance for any help!
Title: Re: Need Audacity help in reducing spike
Post by: Brian Skalinder on April 22, 2007, 02:35:58 PM
At least two options:

Volume envelope or compression (either soft-knee or limiting).  Not positive Audacity's compression works properly, but I think the limiting does (just doesn't sound as good to my ears as softer compression).
Title: Re: Need Audacity help in reducing spike
Post by: taylordb on April 22, 2007, 03:11:08 PM
Thanks Brian.  I'm guessing that I apply the volume envelope or compression to just the affected region?  The spike region is very very small so I'm not sure that the degradation would be too noticeable.
Title: Re: Need Audacity help in reducing spike
Post by: capnhook on April 26, 2007, 06:37:35 PM
If the spike is small, like you say it is, do what I do............zoom in and highlight the spike, and use Amplify ----- but amplify a negative amount of dBs (say, -9dB).  You'll fix it and never even hear what you did, if you do this right.  I weed out loud clapping spikes like this all the time.

Like Brian says, the compressor function is either broken or doesn't work at all (V1.2.4).

VIVE` AUDACITY!

 ;D
Title: Re: Need Audacity help in reducing spike
Post by: gratefulphish on May 04, 2007, 11:23:43 PM
In SF8, as well as Audacity, I use the draw function to correct isolated problems like this.  Once you get used to what the waveforms look like zoomed in, you can easily see where the problem is.  You can always zoom out a little, and then back, if you feel lost.
Title: Re: Need Audacity help in reducing spike
Post by: taylordb on May 05, 2007, 11:06:58 AM
Thanks guys.  I went in and practiced using the draw function.  It took a while to get use to it, but after a while I got pretty good at it.  I was able to get rid of them fine without affecting the sound (at least to me).  Although I don't have any to give, +T's for all your help  :)
Title: Re: Need Audacity help in reducing spike
Post by: dorrcoq on May 05, 2007, 11:08:17 PM
...zoom in and highlight the spike, and use Amplify ----- but amplify a negative amount of dBs (say, -9dB).  You'll fix it and never even hear what you did, if you do this right.  I weed out loud clapping spikes like this all the time.

Now THAT is a hell of a good tip!  Thanks, +T
Title: Re: Need Audacity help in reducing spike
Post by: capnhook on May 05, 2007, 11:33:57 PM
...zoom in and highlight the spike, and use Amplify ----- but amplify a negative amount of dBs (say, -9dB).  You'll fix it and never even hear what you did, if you do this right.  I weed out loud clapping spikes like this all the time.

Now THAT is a hell of a good tip!  Thanks, +T

Backatcha!  Payback for all the great info I get around here  ;) :) ;D
Title: Re: Need Audacity help in reducing spike
Post by: dean on May 06, 2007, 01:26:42 AM
...zoom in and highlight the spike, and use Amplify ----- but amplify a negative amount of dBs (say, -9dB).  You'll fix it and never even hear what you did, if you do this right.  I weed out loud clapping spikes like this all the time.

Now THAT is a hell of a good tip!  Thanks, +T

QFT.  Do this all the time and it's a real time saver.  Additionally, there's a Repeat function in the Effect menu, so you can match the de-amplification percentage each time you highlight a spiked area. Short cut is apple-r.   :)
Title: Re: Need Audacity help in reducing spike
Post by: capnhook on May 06, 2007, 07:13:47 AM
...zoom in and highlight the spike, and use Amplify ----- but amplify a negative amount of dBs (say, -9dB).  You'll fix it and never even hear what you did, if you do this right.  I weed out loud clapping spikes like this all the time.

Now THAT is a hell of a good tip!  Thanks, +T

QFT.  Do this all the time and it's a real time saver.  Additionally, there's a Repeat function in the Effect menu, so you can match the de-amplification percentage each time you highlight a spiked area. Short cut is apple-r.   :)

Ahhhh.....that's what the repeat function can be used for.  +T   
Title: Re: Need Audacity help in reducing spike
Post by: dean on May 06, 2007, 05:44:32 PM
...zoom in and highlight the spike, and use Amplify ----- but amplify a negative amount of dBs (say, -9dB).  You'll fix it and never even hear what you did, if you do this right.  I weed out loud clapping spikes like this all the time.

Now THAT is a hell of a good tip!  Thanks, +T

QFT.  Do this all the time and it's a real time saver.  Additionally, there's a Repeat function in the Effect menu, so you can match the de-amplification percentage each time you highlight a spiked area. Short cut is apple-r.   :)

Ahhhh.....that's what the repeat function can be used for.  +T   

You'll love it!  It's a way of life!   ;)

Backatcha!
Title: Re: Need Audacity help in reducing spike
Post by: detroit lightning on August 15, 2017, 09:53:35 PM
Bumping a super old thread...but just checking if we still feel this amplify by negative db's is still a good option. I've been playing around with compression and the envelope tool for clapping, but this -db option seems like a good idea too.
Title: Re: Need Audacity help in reducing spike
Post by: capnhook on August 15, 2017, 10:01:15 PM
I'm faster at zero-ing in on the spike, and pulling down the envelope nowadays.  Do a few hundred, and you get fast.... 8)
Title: Re: Need Audacity help in reducing spike
Post by: detroit lightning on August 15, 2017, 10:14:51 PM
I'm faster at zero-ing in on the spike, and pulling down the envelope nowadays.  Do a few hundred, and you get fast.... 8)

Is there a difference in sound?
Title: Re: Need Audacity help in reducing spike
Post by: capnhook on August 15, 2017, 11:03:38 PM
I'm faster at zero-ing in on the spike, and pulling down the envelope nowadays.  Do a few hundred, and you get fast.... 8)

Is there a difference in sound?

Do it both ways, invert one, then combine them.  There's the difference.
Title: Re: Need Audacity help in reducing spike
Post by: voltronic on August 16, 2017, 07:46:27 AM
If the spike is in a place where there is music (and not just audience noise between songs), I don't like to use gain reduction, either through the Amplify function or the envelope.  You want to reduce the offending clap / stand hit / drunk person / whatever without reducing the music.

So a compressor is the way to go, but I don't really like Audacity's compressor module.  What I've found works better (for me) is starting with the Hard Limiter and softening it a bit (http://taperssection.com/index.php?topic=163137.msg2221934#msg2221934).
Title: Re: Need Audacity help in reducing spike
Post by: Life In Rewind on August 16, 2017, 09:18:17 AM
Sometimes you can just zoom/select and cut it out completely - and not really miss it...depends on the material.
Title: Re: Need Audacity help in reducing spike
Post by: rocksuitcase on August 16, 2017, 09:25:41 AM
Volt, thanks for the re-post of the Hard Limiter tip. I copied that into my Audacity tips file and will use it. I hate using the negative amplify to do this when music is playing.
Title: Re: Need Audacity help in reducing spike
Post by: voltronic on August 16, 2017, 02:12:40 PM
Sometimes you can just zoom/select and cut it out completely - and not really miss it...depends on the material.

Maybe if it's only a few ms long.  Is that like the opposite of inserting extra frames into movies, a-la Fight Club?
Title: Re: Need Audacity help in reducing spike
Post by: detroit lightning on August 18, 2017, 03:11:52 PM
So, using the negative amplification feature on the non-music, crowd/clapping sections is a game changer for me. It can be tough to get exactly right without hearing the change, but it's minimal, and as long as it's not during the music - it does a great job of balancing things out. The hard limiter is ok, but it always created that weird compressed sound to me. This is a much better option IMO.